Re: [Caml-list] segfault in simple program with 4.02 native

["Török Edwin" <edwin@etorok.net>]

On Fri, 2014-09-05 at 23:18 +0100, Richard W.M. Jones wrote:
> On Fri, Sep 05, 2014 at 11:13:02PM +0100, Richard W.M. Jones wrote:
> > On Fri, Sep 05, 2014 at 06:06:55PM -0400, Ashish Agarwal wrote:
> > > I increased the stack size to 65532, which is apparently the max allowed on
> > > a Mac, and it doesn't change the behavior.
> > 
> > Yup.  I was able to reproduce this on the non-core version, and indeed
> > increasing the stack to unlimited on Linux does not help.
> > 
> > The stack trace is simple:
> > 
> > #0  0x00000000004543f4 in camlPervasives__output_string_1198 ()
> > #1  0x0000000000472093 in camlCamlinternalFormat__output_acc_60624 ()
> > #2  0x0000000000473a32 in camlPrintf__fun_1062 ()
> > #3  0x000000000041e776 in camlApp__entry ()
> > #4  0x000000000041c5f9 in caml_program ()
> > #5  0x0000000000497f7e in caml_start_program ()
> > #6  0x000000000049813d in __libc_csu_init ()
> > #7  0x00007ffff7317d65 in __libc_start_main () from /lib64/libc.so.6
> > #8  0x000000000041c2e9 in _start ()
> > 
> > I'm just installing debuginfo so I can get more symbols ..
> 
> .. although I guess the fact that the generated code in config_j.ml is
> doing a lot of Obj.magic would be the first place to be suspicious.
> 
> eg:
> 
>     let (x : postgres) =
>       {
>         host = Obj.magic 0.0;
> ...
> 
> where the host field has declared type string.  Really?

There's also this, and a lot of Obj.set_field too
  postgres = Obj.magic 0.0;

FWIW it triggers an assertion failure with -runtime-variant d even
before it starts parsing:

./app.native 
### OCaml runtime: debug mode ###
Initial minor heap size: 2048k bytes
Initial major heap size: 3840k bytes
Initial space overhead: 80%
Initial max overhead: 500%
Initial heap increment: 15%
Initial allocation policy: 0
file memory.d.c; line 548 ### Assertion failed: Is_in_heap(fp)

Best regards,
--Edwin